Goodman furnace 4 flashes: limit circuit open (single-LED boards)

Furnace control display or LED

4 flashes

“Primary or auxiliary limit circuit is open.”

GMES9* / GCES9* / AMES9* / ACES9* / VMES9* / VCES9*, GMES80 / GCES80 / AMES80 / ACES80 / VMES80 / VCES80, GMSS9* / GCSS9* / AMSS9* / ACSS9*, GKS9 / AKSS92, GMS8 / AMS8 / GDS8 / ADSS8 · IOG-2020J p. 41; IOG-2021H p. 30; IOG-2009Q p. 43; RS6612004R2 p. 50; RS6612006 p. 39
Technician

What it means

On Goodman and Amana furnaces with a single diagnostic LED, four flashes between pauses mean the control found a limit circuit open. The circulator blower runs continuously and the furnace does not heat IOG-2020J, p. 41; RS6612012R8, p. 45.

The wording depends on the table. “Primary or auxiliary limit circuit is open.” is used for the GMES9, GMSS9 and GKS9, the 2013 GMS8 manual and the 2022 GMES80 instructions IOG-2020J, p. 41; IOG-2009Q, p. 43; RS6612004R2, p. 50; RS6612006, p. 39; IOG-2021H, p. 30. “Primary limit circuit is open.” is used in the 2019 GMES80 service manual, the 2017 GMS8 revision and the GMH95, GME95 and GME8 manuals RS6621003, p. 37; RS6612006R7, p. 44; RS6612003R2, p. 55; RS6612005R1, p. 50; RS6621001R2, p. 36.

The GMES9 and GMSS9 tables give the same causes: a faulty primary or auxiliary limit switch; insufficient conditioned air over the heat exchanger from blocked filters, restrictive ductwork, an improper circulator blower speed or a failed circulator blower; and loose or improperly connected wiring IOG-2020J, p. 41; RS6612012R8, p. 45.

On three-color boards four flashes mean something else (see the notes below).

Check these first

The owner’s manual gives no step for this code. Its instruction for a flashing LED HIG-2002A, p. 8:

Count the flashes between pauses through the blower compartment sight glass and write the number down HIG-2002A, p. 8. If your LED flashes red, amber or green, use the notes below instead.
Shut the furnace down: thermostat to its lowest setting (the control closes the gas valve and the blowers stop after a delay), remove the burner compartment door, move the gas valve’s ON/OFF switch to OFF, close the external manual gas shut-off valve and put the door back HIG-2002A, p. 6. Before the gas control goes to OFF, the start-up steps and the label also turn off the electrical power to the furnace; the label says to do so if service is to be performed HIG-2002A, pp. 6, 9. Move the gas control by hand only, never with tools; if it will not move, call a qualified service technician HIG-2002A, p. 9. Full steps: shutting the furnace down.
Contact a qualified servicer HIG-2002A, p. 8.

The manual asks you not to go further: “Do not attempt repairs yourself” HIG-2002A, p. 8, and “do not remove any internal compartment covers” HIG-2002A, p. 6.

Blocked filters are among the causes. Filter changes are the one maintenance task the owner’s manual leaves to you HIG-2002A, p. 6. It says to disconnect electrical power before removing filters, to inspect, clean or change filters every two months or as required, and never to run the furnace without one HIG-2002A, p. 7; its checklist says to check them at least once a month HIG-2002A, p. 8. That checklist runs in this order: thermostat, circuit breakers and fuses, filters, return and supply grilles, then intake and vent terminations on high efficiency furnaces. The manual gives it for a furnace whose LED is not flashing, so it is not a fix for 4 flashes.

When to call a licensed technician

The corrective actions in the GMES9 and GMSS9 tables IOG-2020J, p. 41; RS6612012R8, p. 45:

Checking the primary or auxiliary limit and replacing it with the proper part.
Checking the ductwork for blockage and removing obstructions.
Checking the circulator blower speed and performance, correcting the speed or replacing the blower.
Tightening or correcting wiring connections.

The GMES9 and GMSS9 tables say to turn power OFF before any repair IOG-2020J, p. 41; RS6612012R8, p. 45. On GMEC96 and GMEC80 boards, the check list for red 4 flashes is the temperature rise, duct static, gas pressure, burner alignment, orifice plate position and the wiring to all limits GMEC96: IOG-2011U, p. 55; GMEC80: RS6621005R1, p. 29.

Notes for different models

Board or series	Code	Meaning in the table	Source
Single LED (series listed at the top of this page)	4 flashes	“Primary or auxiliary limit circuit is open.” or “Primary limit circuit is open.”	IOG-2009Q, p. 43; RS6612003R2, p. 55
GMEC96, GMEC80	Red 4 flashes	“Open limit circuit, main limit, aux limit, or roll out switch”	IOG-2011U, p. 55 (GMEC96); RS6621005R1, p. 29 (GMEC80)
GMEC96, GMEC80	Red 5 flashes	“Limit & rollout circuit open for 15 minutes. Open control board fuse or rollout switch”	IOG-2011U, p. 55 (GMEC96); RS6621005R1, p. 29 (GMEC80)
GMEC96, GMEC80	Red 11 flashes	“Open limit switch circuit for more than 5 minutes”	IOG-2011U, p. 55 (GMEC96); RS6621005R1, p. 29 (GMEC80)
MES96U, GMES80*U, 2019 manuals	Red 4 flashes	“Primary limit insert; or aux limit circuit is open.”	RS6612017, p. 20; RS6621006, p. 16
Three-character display	EE3	“Primary limit circuit is open”	IOG-2037A, p. 41
ComfortNet, variable speed and Ultra-Low NOx boards	EEd	“Aux limit switch open (blower compartment)”	IOG-2015L, p. 49
Older ComfortNet two-character boards	E3 (thermostat: HIGH LIMIT OPEN)	“Primary limit or auxiliary limit circuit is open. Rollout limit circuit is open.”	RS6612010R6, p. 48

The MES96U and GMES80*U rows above come from the 2019 service manuals. The 02/2022 installation instructions for these series have their own flash tables, worded differently IOG-2013F, pp. 33–34; IOG-2019G, pp. 26–27.

On GMEC96 and GMEC80 boards the limit codes are split by time: red 4 flashes for an open limit circuit, red 11 flashes when it stays open for more than 5 minutes, and red 5 flashes when the limit and rollout circuit stays open for 15 minutes GMEC96: IOG-2011U, p. 55; GMEC80: RS6621005R1, p. 29.